There were two cases in this exercise where I felt that my word should be acceptable but it was not given as an option:
1.Your answer: Janine était professeur de français avant; whereas mine was : Autrefois, Janine était....... Why would autrefois not be acceptable?
2. For such a short word, 'so' can be confusing. The English phrase was "so that wasn't too complicated!". Would ainsi be correct? I can imagine the english word 'thus' in this context.